spiderpigcity Posted February 23, 2008 Share Posted February 23, 2008 So you're trying to tell us that standard OEM discs and pads are better than any proper race stuff? i think more to the point the clio doesn't need anything better that's why renault use what they do. the car is light enough, and these brakes do the job just fine. end of Quote Link to comment Share on other sites More sharing options...
Terminator Posted February 23, 2008 Share Posted February 23, 2008 ....................................................... bottom line do you want bling or performance. :p Exactly Quote Link to comment Share on other sites More sharing options...
SimonB Posted February 23, 2008 Share Posted February 23, 2008 When you're talking racing cars, the main reason for choosing the brakes they do is what the regulations allow. They would all go for the largest they could if allowed to! Obviously if you were preparing a Supra for racing or track use only you would strip as much weight as possible and end up with a bare shell. Most people use their cars on the road mainly, and still want to do track days etc, so that's not practical. Quote Link to comment Share on other sites More sharing options...
paul mac Posted February 23, 2008 Author Share Posted February 23, 2008 Paul I'll happy spend some of it on some Top Secret light weight Acrylic (driver and passenger) windows, GT carbon fibre mirrors and 4.7kg GReddy Ti-R exhaust ps. I'll keep thinking, I'm sure I can find more things to sell you ( this in tech scratch that idea!) thanks for the offer of spending my hard earned Nic pm me a price delivered for the Greddy . . meanwhile back on topic allthough Matt makes some good points and has stimulated some good discussion it does not really answer my original question of is the after market stuff proven to be better than stock, roll on the summer Quote Link to comment Share on other sites More sharing options...
colsoop Posted February 23, 2008 Share Posted February 23, 2008 Reading through the thread Paul i don't think your set up is where matt craven is aiming his words as yours is a production car set up which i assume has had the relevant testing that only OEM's do. I assume he is talking about the D2 and similar setups that can't have had the same level of testing as OEM. Quote Link to comment Share on other sites More sharing options...
Wez Posted February 23, 2008 Share Posted February 23, 2008 Top Secret light weight Acrylic (driver and passenger) windows Have you got some more info on these Nic? Quote Link to comment Share on other sites More sharing options...
colsoop Posted February 23, 2008 Share Posted February 23, 2008 Have you got some more info on these Nic? Quote Link to comment Share on other sites More sharing options...
Thorin Posted February 23, 2008 Share Posted February 23, 2008 if you read the post carefully i said in that scenario yes they where. If you read some of my posts you'll see I'm a big advocate of OEM stuff. The larger stock Supra brakes are excellent, and unless you're a big track day fanatic they'll do you fine. ...However, the scenario you are talking about, proper race car, only driven on the track, brakes given a lot of abuse and repeated high speed stops... You're telling me stock OEM discs and pads are best for your Clio? I'd be very surprised if that was the case. Quote Link to comment Share on other sites More sharing options...
Nic Posted February 23, 2008 Share Posted February 23, 2008 Have you got some more info on these Nic? Not really, I just know they make them for the Supra, I can get a price if you want. Quote Link to comment Share on other sites More sharing options...
Alex Posted February 23, 2008 Share Posted February 23, 2008 Bit too much pimping going on in a tech thread Quote Link to comment Share on other sites More sharing options...
Wez Posted February 23, 2008 Share Posted February 23, 2008 Not really, I just know they make them for the Supra, I can get a price if you want. PM me a price matey Quote Link to comment Share on other sites More sharing options...
Nic Posted February 23, 2008 Share Posted February 23, 2008 Bit too much pimping going on in a tech thread Quote Link to comment Share on other sites More sharing options...
spiderpigcity Posted February 23, 2008 Share Posted February 23, 2008 how about forget the big brembos and look at an aftermarket air brake like on my mates merc slr! i bet you havn't got one of those in stock hey Nick? :D Quote Link to comment Share on other sites More sharing options...
paul mac Posted February 23, 2008 Author Share Posted February 23, 2008 how about forget the big brembos and look at an aftermarket air brake like on my mates merc slr! :D care to explain Matt i'm lost, i thought air brakes were for trucks Quote Link to comment Share on other sites More sharing options...
bignum Posted February 23, 2008 Share Posted February 23, 2008 Isent it that rear spoiler thing that flips up on the back when braking from speed ? Quote Link to comment Share on other sites More sharing options...
SUPRASUZUKI Posted February 23, 2008 Share Posted February 23, 2008 .....fast and the furious........its a top film. You were doing really well until you said that!! Quote Link to comment Share on other sites More sharing options...
spiderpigcity Posted February 23, 2008 Share Posted February 23, 2008 yes it flips up when braking hard from certain speeds and it leaves your taties on the front bumper its effective! Quote Link to comment Share on other sites More sharing options...
spiderpigcity Posted February 23, 2008 Share Posted February 23, 2008 whos gonna be the first to try and make one then? a couple of pistons and some pnuematics and a surf board:D:D, can't be that hard? Quote Link to comment Share on other sites More sharing options...
Nic Posted February 24, 2008 Share Posted February 24, 2008 how about forget the big brembos and look at an aftermarket air brake like on my mates merc slr! i bet you havn't got one of those in stock hey Nick? :D Veilside wing anyone? Quote Link to comment Share on other sites More sharing options...
Alex Posted February 24, 2008 Share Posted February 24, 2008 lol VS wings knock off 6-10mph in a 1mile standing start drag. Quote Link to comment Share on other sites More sharing options...
spiderpigcity Posted February 24, 2008 Share Posted February 24, 2008 must give some downforce as a sacrafice then? Quote Link to comment Share on other sites More sharing options...
Alex Posted February 24, 2008 Share Posted February 24, 2008 must give some downforce as a sacrafice then? Probably more drag than downforce...as the two do not follow each other. Quote Link to comment Share on other sites More sharing options...
TLicense Posted February 24, 2008 Share Posted February 24, 2008 There's quite a bit of confused logic being bandied around here. Right to start off with, let me tell you about my history with brake systems. For the last 10 years I've worked in developing aerodynamic attributes of F1 cars. Approximately 2 years of that (albeit spread over 8 years of that period) has been spent developing brake systems. Whilst the majority of the work I've been involved with has been to do with how to cool the brake system, I've also been involved in the design of the brake system from a clean sheet in an effort to produce a brake system design that is at worst sympathetic to the air flow, and at best utilises the air flow to improve vehicle performance. So in all, it's fair to say I've been around the block when it comes to brakes. The "brake horsepower" mentioned in the table posted refers to the amount of work done by the braking system to stop a car. Using my very rusty math's, to stop a 1600Kg Supra travelling at 100mph in 5 seconds would require an average of 708084 Joules / second of work to be done = 962 metric HP. This is basically the work done to convert 3540418.6 Joules of kinetic energy into other forms of energy (predominantly heat) in 5 seconds, which is exactly what the braking system is doing. According to the table given, if the TT 4 pots can do work at a rate of 1665HP, and the tyres were able to cope with the rate of deceleration, then it should be possible to stop the car from 100mph in a little under 3 seconds.... Anyway, the effective ability of the brake system to do this heat transfer is what we're essentially talking about. This is dependant on a number of things. Now there's plenty of resource available on line as to how brakes work, but to summarise:- Braking performance is a function of the friction coefficient of the pad, the clamping force placed upon the pad by the calliper pistons and the distance from the centre of the wheel to the centre of pressure generated by the pad. A secondary function is the ability of the system to transfer heat from the pad / disc mating face elsewhere. There's nothing less or nothing more to it. However optimising those functions is where things tend to get tricky. Increasing the area of the pad face will not increase the friction between the pad and the disc. Brake pads are the size they are as a function of other factors. Primarily to do with the size and number of calliper pistons. (Increasing the size of the piston increases the force that is being exerted on it by the hydraulic fluid, which increases the clamping force of the pad) However there are obvious geometric limitations as to how large a piston can be. Increasing the number of pistons does not necessarily mean better braking ability though. The clamping force on the pad is a function of the hydraulic pressure being exerted on the piston face, and the area of that piston face. Increasing either will increase the clamping force of a brake pad, and in turn increase the braking ability of the brake system. However the big problem is calliper stiffness. In fact it's not a big problem, it's a MASSIVE problem. As the callipers get bigger and bigger it becomes more and more difficult to make the calliper strong. Generally, unless you're willing to spend tens of thousands of pounds on callipers made from exotic aluminium alloys like MMC, you'll be left with standard aluminium, which is pretty weak. The problem with that is as the callipers get longer to fit more pistons in, you get more deflection of the calliper. Basically the force of the piston on the pad is equally exerted onto the calliper itself, and it tries to bend the calliper open. For years 6 pot callipers were believed to be the best compromise between the number of pistons vs the length of the calliper, but with modern design practices it's possible for more elaborate 8 pot callipers to have the same stiffness as 6 pots. 4 Pot callipers are inherently stiffer than 6 pot's, however the problem is getting enough piston area into the calliper to give sufficient clamping force. It's a fine balance..... If you look at most quality calliper designs you'll also notice that the pistons area not all the same size. Even the two outer pistons will be different sizes. This is to help reduce the amount of tapered wear that would exist of you had all 3 pistons the same size. It's a balance between performance and longevity. You'd be pretty hacked off if you had a fantastic brake set-up but had to change the pads every few thousand miles because one end of the pad was worn to the backing whilst the other end was only half worn. Where the largest confusion comes into play is to do with heat transfer and brake fade. Brake fade comes in two distinct forms. One is when the friction coefficient of the brake pad is reduced due to the pad material being outside of it's temperature range, the other is when the same thing happens to the brake fluid. Each have their own distinct symptoms, but have similar solutions. Pad fade is identified by the brake pedal going very hard, but giving no retardation. Boiling brake fluid is identified by the pedal going spongy as the boiled fluid which is now gas, compresses. The simplest solutions for both mean making sure that the compound of the pad, and the fluid is in the right heat range. The second solution is making sure that the components of the brake system are as capable as possible in removing the heat from the above critical areas. Solutions involve correct material choice for discs and associated components, and ensuring that they have sufficient cooling. Material choice is usually driven by suppliers. You want a disc that has as low a specific heat transfer as possible. You basically want the material to absorb as much energy as possible before it increases by 1 degree. (Remember all it's doing is converting energy to heat - you just want it to have to absorb lots of it before it actually increases by 1 degree C) If you have a poor quality disc, then the disc is going to get hot quickly and will soon approach the temperature of the pad. When that happens the rate of heat transfer from the pad to the disc get's smaller, which means the pad stays hotter for longer. Most discs nowadays have various "vented" designs. Vanes that pump the air through the inside of the disc in an attempt to cool it. However it's also possible to cool the disc from the outside by making cooling ducts. The problem with these is it's far, far, far easier to get them wrong than it is to get them right. A simple example is do you want air to go from the inside of the wheel to the outside, or do you want it to go from the outside to the inside? Which would be better for cooling? By producing a duct that aided the air to go in one of the directions will help the cooling, but if you get it wrong in all likely hood it will actually hinder it. Also where do you want to point the duct? At the disc face? At the calliper? Get it wrong and you can end up creating a higher pressure region in an area where you want a low pressure region to help pull air in from another area. Then there is how fitting a duct will affect the actual downforce / drag profile of the vehicle which is a whole story on itself. My honest opinion with regards to ducting... unless you really know what you're doing, leave it well alone. I know there's maybe a few area's here that I've skipped over, but there's only so much someone can type (and remember ) in one go. But if anyone has anything specific that they'd like to ask, then I'm more than happy to try and answer any questions if I know the answers. Hope that clears up a few things though..... Quote Link to comment Share on other sites More sharing options...
juanchan Posted February 24, 2008 Share Posted February 24, 2008 That's a cracking summary Tony! On the subject of all the heat transfer going on, I'm assuming that the wheel design will play a role in the ducting of air to aid cooling. Would that be another argument to stick with stock wheels over some fancy 18s/19's? Would the wheel material need to be good at absorbing heat before increasing in temperature too? As if the wheel gets hot, may it hinder heat being disapated(sp) from the callipers? Quote Link to comment Share on other sites More sharing options...
Wez Posted February 24, 2008 Share Posted February 24, 2008 Nice post Tony Quote Link to comment Share on other sites More sharing options...
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